A number of helicopters and rotorcraft using ramjets or the like, mounted on the tips of the rotors, are known in the art. Probably the most famous and most operable of these was the American Helicopter XA-8/XH-26 “Flying Jeep” aircraft. The Model XA-8 single-seat lightweight helicopter was a light, collapsible machine, which could be used as both a light observation craft and as an air-droppable rescue vehicle for downed aircrew. The XH-26 was powered by two pulse-jet engines, one fixed to the tip of each main rotor blade, and could burn virtually any type of fuel. Another novel feature of this aircraft was the use of a single-bladed, counterbalanced tail-rotor (presumably for packaging reasons). The Army and Air Force jointly evaluated the five XH-26 prototypes from 1952 to 1954. The machines were found to be robust in construction and relatively simple to operate, but neither service procured the type in quantity. One problem noted by users was that the pulse-jet engines were quite loud when in use, and the aircraft exhibited a “screaming” noise when in use.
Other helicopters using thrust engines on rotor tips as well as air jets and other devices are known in the art. The following Patents and published Patent Applications, all incorporated herein by reference, were discovered in a Prior Art search commissioned by Applicant.
U.S. Pat. No. 3,417,825, entitled “HELICOPTER ROTOR AND TURBINE ASSEMBLY” (RAMME) discloses a helicopter with counter rotating rotor blades that are driven by jet engine exhaust. Thus device, rather that using wing-tip pulse-jets, uses a rather cumbersome radial turbine mounted to the blade. Note the lack of tail rotor. The device does appear to use a pitch and cycle control.
U.S. Pat. No. 4,589,611, entitled “Air jet reaction contrarotating rotor gyrodyne” (RAMME) discloses a contra-rotating rotor gyro-dyne which has twin turbofan engines providing forward jet thrust with a bypass air fraction for rotating rotors. This design uses jet exhaust ducted into the tips of counter-rotating rotors. See FIG. 3. The design appears to use a pitch control. See FIG. 6. The apparatus appears to be directed more toward a gyrocopter design than a helicopter.
U.S. Pat. No. 3,176,413 (DORNIER) discloses a helicopter with a jet-tip type propulsion system. This apparatus is disclosed as a “training apparatus” rather than as a flyable helicopter. The design does show the use of wing-tip jet engines.
U.S. Pat. No. 2,437,700 (MACFARLAND, JR.) discloses a dual rotor helicopter with reaction motor propulsion. This design uses rotating jets, but they are not attached to the wing tips, but rather to a separate boom. A gearbox transmits this energy to counter-rotating rotor blades.
U.S. Pat. No. 2,509,359 (MARGOLIS) discloses a rotary reaction motor. This reference broadly teaches the concept of using a pulse-type jet to power a propeller. Note how the jet angle may be changed to alter thrust.
U.S. Pat. No. 2,710,067 (SFORZN) discloses a rotorcraft with rotor tip propulsion. This reference also teaches the use of a wingtip jet rotor using an engine driven compressor. Note the lack of counter-rotating rotors, however.
U.S. Pat. No. 2,594,788 (MORAIN) discloses a blade tip propulsion system. This reference is directed toward solving one of the detailed problems in providing fuel to rotor-tip mounted engines.
U.S. Pat. No. 3,371,718, entitled “ROTARY JET REACTION MOTORS,” (BACON) discloses a rotary jet reaction motor for wing blades. This reference also teaches the use of wing-tip mounted jets. Note the pitch control gears in FIG. 2.
U.S. Pat. No. 3,699,771, entitled “ROTARY WING AIRCRAFT LIFT AND PROPULSION METHOD AND SYSTEMS” (CHELMINSKI) discloses a rotary wing aircraft lift and propulsion method and system in which burner thruster units mounted on the lift-producing rotor at a position spaced radially from the axis of the rotor generate moments to turn the rotor about its axis. This reference also teaches the use of wing-tip mounted jets in a single rotor configuration.
Published U.S. Patent Application 20040000614A1 entitled “Method and apparatus for lifting and propelling rotorcraft (LEYVA) discloses a lifting and propelling apparatus for a rotorcraft, which has pulse detonation engines, which impulsively detonate fuel-air mixtures to generate and apply thrust forces to rotor assembly. This recent reference to GE Research shows the use of a jet mounted to the HUB of the rotor (FIG. 2), the rotor itself (FIG. 3) and within the rotor (FIG. 4). A pulse detonation engine is described.
U.S. Pat. No. 3,930,625 (KRIVKA) discloses a steam jet powered helicopter, which has shroud surrounding blade nozzles to condense and recycle steam. See FIG. 9. See paragraph at column 5, line 57 for description of FIG. 9.
U.S. Pat. No. 5,149,014, entitled “Rotary wing aircraft” (FALLER) discloses a rotation compensated helicopter drive, which incorporates hollow blades and compressed air ducted to exit slots from central turbine.
U.S. Pat. No. 5,984,635, entitled “Keller pressure jet rotor system” (KELLER) discloses a pressure jet rotor system in helicopters.
U.S. Pat. No. 3,768,926, entitled “PULSE JET ROTOR DRIVE FOR HELICOPTER” (PEGG) discloses a pulse-jet system for driving a rotary wing aircraft. In a first embodiment the tips of the rotors of a rotary wing aircraft are provided with “U”-shaped valveless pulse jet engines having an annular scoop adjacent to the lip of the inlet to provide fresh air thereto at increased air velocity.
U.S. Pat. No. 6,390,413, entitled “Years two thousand of new safety helicopter” (CHIU) discloses a system for landing a falling helicopter in an accident with at least one parachute mounted on the helicopter, and speed reduction jets mounted at belly portion of helicopter.
U.S. Pat. No. 3,873,049, entitled “Flying machine” (HORSDAL) discloses a VTOL flying machine with four rotors producing upward thrust with rotor slots to provide forward thrust.
U.S. Pat. No. 5,791,592, entitled “Helicopter with coaxial counter-rotating dual rotors and no tail rotor” (NOLAN) discloses a helicopter with coaxial counter rotating dual rotors and no tail rotor. A pair of engines drive a single rotating shaft on which a pair of rotors are mounted.
U.S. Pat. No. 3,722,830, entitled “HELICOPTER TYPE VEHICLE” (BARBER) discloses a helicopter type vehicle having coaxial counter rotating propellers above the cabin of the vehicle, each propeller being fixed in pitch as opposed to conventional helicopter propellers which vary in pitch during rotation of the propeller.
U.S. Pat. No. 3,610,555, entitled “FLUID-DRIVEN ROTARY WING AIRCRAFT” (NAGLER) discloses a rotary wing aircraft which operates during takeoff and landing as a conventional helicopter employing the combined outputs of main and auxiliary compressors.
U.S. Pat. No. 6,216,446, entitled “Valveless pulse-jet engine with forward facing intake duct” (STRAM) discloses a self-starting, self-spirating valveless jet engine which has a supersonic fuel nozzle fitted into the vaporizer tube, positioned in front and to the center of the flared mouth of the first stage intake duct.
Published U.S. Patent Application 20020125368A1, entitled “Ultralight coaxial rotor aircraft” (PHELPS) discloses an ultra-light coaxial dual rotor helicopter includes air-inflated pontoon skids, pitch and roll control by actuators tilting the rotor axis, and yaw control paddles.
U.S. Pat. No. 5,370,341, entitled “Ultralight helicopter and control system” (LEON) discloses an ultra-light helicopter and control system with a single motor drive for counter-rotating rotors via a bevel gearing or hydraulic pump-motors.
U.S. Pat. No. 1,133,660 (PAPIN) discloses a helicopter with air that pushes out of rotor tips.
U.S. Pat. No. 2,831,543 (MATTHEWS) discloses a helicopter with jet pressure driven rotors.